1. Field of the Invention
The present invention relates to a stent delivery device which is used in combination with an endoscope to insert a stent into a body cavity of a patient and place it there.
2. Description of the Related Art
To discharge bile from a bile duct, the following medical treatment is performed. First, the insertion section of an endoscope is inserted into a body cavity. Then, a stent is inserted through a channel of the endoscope and guided to the narrowed area of the bile duct. The stent is placed at the narrowed area of the bile duct. The bile in the bile duct is discharged through the lumen of the stent.
As disclosed in Jpn. UM Appln. KOKAI Publication No. 63-20854, a stent is a comparatively soft hollow tube formed of a macromolecule compound such as poly-ethylene, silicone rubber, or the like. The stent is provided with a flap at each end of the outer wall. With this structure, the stent is prevented from slipping off.
To permit the stent of the above structure to be guided into the body cavity through the use of the endoscope and placed at the narrowed area of the bile duct, the following manual procedures are performed:
As shown in FIG. 10A, an elongated guide wire 3, which is a flexible wire, is inserted through the forceps channel 2 of the insertion section 4 of an endoscope 1. The guide wire 3 is guided to a bile duct 5 together with the insertion section 4 of the endoscope 1. Then, the guide wire 3 is moved forward and inserted through a narrow portion 6 by operating the proximal end of the guide wire 3. As shown in FIG. 10A, a stent 7 is fitted around the proximal end of the guide wire 3 and slid along the guide wire 3. Subsequently, a pusher tube 8 is fitted and slid.
As shown in FIG. 10B, the stent 7 is pushed by means of the pusher tube 8, and the guide wire 3 passed through the narrowed area 6 is used as a guide then. The stent 7 in this state is inserted through the narrowed area 6 and placed there.
U.S. Pat. No. 5,921,952 discloses a drainage catheter delivery system wherein a pusher tube and a stent are coupled together by means of a thread. As will be detailed below, the drainage catheter delivery system is advantageous in that the stent pushed in too much can be pulled back when the pusher tube that is connected to the stent by means of the thread is pulled back.
In the drainage catheter delivery system, an insertion hole in which the thread is inserted is formed at the distal end portion of the pusher tube. The stent is provided with a hole defined by flaps. A thread (a suture), jointed with a guide wire, goes through the hole of the stent and is inserted through the insertion hole of the pusher tube and fastened. In this manner, the stent and the pusher tube are coupled together.
If the stent is pushed in too much, the pusher tube is moved back, and the stent is pulled by the thread and returned to the original position. When it is desired that the stent be placed at the narrowed area, the stent is first guided to the narrowed area and then the guide wire is pulled back. When the distal end portion of the guide wire is disengaged from the thread, the thread is pulled off the stent. In this manner, the stent and the pusher tube is disconnected.